In recent years, a wobble determination device and a wobble determination method have been known which detect the wobble of a host vehicle on the basis of white line information that is input from, for example, a white line detection sensor, determine the degree of wakefulness of the driver of the vehicle on the basis of the wobble state of the vehicle, and issue a warning to the driver when it is assumed that the consciousness of the driver has been degraded from the degree of wakefulness.